Peristaltic pump

ABSTRACT

Peristaltic pump having an elastically yieldable pipe having a fixed configuration imparted thereto by a support ramp abutting the pipe. At least three rotatable rollers mounted on a rotor are made to travel in a closed path and alternately cause compression of the pipe against the support and decompression of the pipe. The path of the rollers, the spacing between the rollers and the configuration of the pipe are such that, when the downstream roller moves away from the pipe an upstream element already closes the pipe and causes the fluid to progress as the downstream roller causes a decompression of the pipe. The intermediate roller progressively compresses the pipe so as to ensure an exact volumetric compensation at each instant of the decompression due to the downstream roller by the compression due to the intermediate roller.

United States Patent 1191 Molimard 541 PERISTALTIC PUMP [75] Inventor: RobertMolimard, Chevilly-Larue,

France [73] Assignee: Laboratories Jacques Logeais, lssy Les Moulineaux, France 221 Filed: Au'g.28, 1971 211 AppLNQ: 175,129

[30] Foreign Application Priority Data Dutler .;..4l7/477 Clemens v.417/477 11 3,724,974 1 1 Apr. 3, 1973 Primary Examiner-William L. Freeh Assistant Examiner-Richard E. Gluck Attorney-Dike, Bronstein, Roberts & Cushman 571 7 ABSTRACT Peristaltic pump having an elastically yieldable pipe having a fixed configuration imparted thereto by a support ramp abutting the pipe. At least three rotatable rollers mounted on a rotor are made to travel in a closed path and alternately cause compression of the pipe against the support and decompression of the pipe. The path of the rollers, the spacing between the rollers and the configuration of the pipe are such that, when the downstream roller moves away from the pipe an upstream element already closes the pipe and causes the fluid to progress as the downstream roller causes a decompression of the pipe. The intermediate roller progressively compresses the pipe so as to ensure an exact volumetric compensation at each instant of the decompression due to the downstream roller by the compression due to the intermediate roller.

10 Claims, 10 Drawing Figures PATENTEUAPR 3 I975 SHEET 2 [IF 3 PATENTEDAPR 3 I975 SHEET 3 OF 3 Fig. 10

The present invention relates to peristaltic pumps of the type in which an elastically yieldable pipe is periodically compressed against a support face which imparts to the pipe a fixed configuration by at least one roller or other moving element which travels through a path which encounters said configuration, the roller or rollers urging the fluid contained in the pipe in the downstream direction as they travel along and compress the pipe.

These pumps have two main drawbacks.

First, when the roller which is the nearest tothe outlet of the pump starts to cease its compressing action on the pipe, a suction effect is produced in the downstream portion of the pipe which tends to return'a part of the previously-discharged fluid in the upstream direction and this results in an alternating motion in the progression of the fluid.

Secondly, the movement in the downstream direction of another roller which starts its upstream travel produces by friction a longitudinal elongation of the pipe which, in retracting, creates a second factor in the reflux of the fluid. v

Further,'this elongation of the pipe is reproduced in regular cycles and may cause, in addition to wear, a progression of the pipe which has for result an undesirable displacement of the position of the pipe against its support face in the body of the pump. I

An object of the invention is to remedy these draw 7 tion of the downstream roller on the stages of operation of the pump during the rotation of the rotor;

FIGS. 5, 6 and 7 are sectional views, taken along lines 5-5, 6-6 and 7-7 of FIGS 2, 3 and 4, of the acpipe in the positions in FIGS. 2, 3 and 4 respectively; and

FIG. 8 is a diagrammatic top plan view of a fixed circular configuration given to the pipe and the relative positions of the three rollers at one stage of operation of the pump during the rotation of the rotor,

FIG. 9 is a diagrammatic top plan view of a fixed sinusoidal configuration given to the pipe and the relative positions of a number of rollers at one stage of operation of the pump during the rotation of the rotor and FIG. 10 is a diagrammatic top plan view of a fixed rectilinear configuration given to the pipe and the relative position of a number of rollers at one stage of operation of the pump during the rotation of the rotor.

In the illustrated embodiment, the pump comprises a base 1 constituted by a circular plate on which is disposed an annular element 2.

. Theannular element 2 is centered on the base 1 by means of an annular projection 3 on the base which cooperates with a corresponding recess 4 in the body 2.

backs and to provide a peristaltic pump of the afore- I mentioned type which is so improved as to ensure constant fluid flows and which can consequently be employed, with very high reliability, in particular for perfusions of liquids having a low flow rate, such as those in certain medical treatments, it being ensured that there is no reflux of the blood from the patient in the delivery end of the pipe of the pump and consequently no risk of possible coagulation at this point.

The invention provides a peristaltic pump comprising a support ramp for an elastically yieldable pipe which imparts to the pipe a fixed configuration, and at least three pressing rollers or other moving elements which are caused to travel in a path which'encounters said configuration so as to compress the pipe and move away from the pipe alternately, the fixed configuration imparted to the pipe by the ramp, the path of the rollers and spacing between the rollers being such that when the downstream roller moves away from the pipe an upstream roller already closes the pipe and causes the fluid to progress as the downstream roller causes a decompression of the pipe, the intermediate roller located between the upstream roller and downstream roller progressively compressing the pipe so as to ensure an exact volumetric compensation, at each instant, of the decompression due to the downstream roller by the compression due to the intermediate roller.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a sectional view of a cording to the invention;

FIGS. 2, 3 and 4 are diagrammatic top plan views of the fixed configuration given to the pipe and the relative positions of the three rollers in three different peristaltic pump ac-' The element 2 has in its upper part a horizontal, radially inwardly-extending flange 5 and a shoulder 6.

The shoulder 6 co-operates with a recess 7 of complementary shape in an annular element 8 whose outer periphery is circular and has the same diameter as the element 2 and base 1 but whose inner periphery has a special shape in plan which will be described hereinafter. 1

The inner face of the element 8 is parallel to its axis and makes a right angle with the horizontal flange 5 of the element 2.

The element 8, the element 2 and the base 1 are fixed together, for example, by bolts (not shown) which extend axially therethrough and are screwthreadedly engaged in the base 1. The elements 2 and 8 and the base 1 constitute a body of the pump.

The element 2 defines a circular cavity in which the mechanism of the pump is located.

This mechanism comprises a vertical drive shaft 9 having at its lower end a hollow enlarged portion 10 which extends through a center aperture 11 in the base 1 and is supported in the latter by a rolling bearing 12.

On the shaft 9 there is freely rotatably mounted a circular roller-carrying plate 13 having a hollow hub 14 provided with a knob 15 whereby it is possible to rotate the plate 13 on the shaft 9 manually.

The plate 13 has on its lower face an annular groove 16 defining a center portion 17 having a diameter corresponding'to that of the immediately adjacent part of the enlarged portion 10.

The center portion 17 is connected to the portion 10 by a suitable coupling means of the freewheel type so that the plate 13 can be driven in rotation in one direction by the shaft 9 and can also be driven directly in the same direction by the knob 15 when the shaft 9 is I stationary. In the illustrated embodiment, this coupling is of a known type comprising a coil spring 18 surrounding the portions 10 and 17.

The plate 13 carries three rollers 19 which are rotatably mounted by means of rolling bearings 20 disposed in recesses provided in the plate and angularly evenly spaced apart and disposed at a given distance from the axis of rotation of the shaft 9 and plate 13.

Each roller 19 has a spindle 21 which extends through the plate and a lower end portion which extends downwardly beyond the plate and is fixed to a gear pinion 22. Each pinion 22 meshes with a ring gear 23 which has internal gear teeth and is fixed to the element 2.

The plate 13 is preferably positioned in the element 2 by means of a rolling bearing 24 whose outer ring is fixed to the element 2 and whose inner ring is fixed to the periphery of the plate 13.

This mechanism operates in the manner of a planetary gear device. The plate 13 is a planet gear carrier whose planet gears 22 mesh with the ring gear 23.

When the plate 13 is driven in rotation by the shaft 9 or manually by means of the knob 15, the gear pinions 22 meshed with the ring gear 23 are driven in rotation and thus rotate the rollers 19.

The pump is completed by an elastically yieldable pipe 25, for example of rubber or any other appropriate material having such characteristics of elasticity that it automatically assumes its initial shape after having been flattened.

The pipe 25 is disposed in the right angle defined by the upper horizontal face of the flange and the inner peripheral face of the element 8, the pipe being interposed between and bearing against this inner face and the rollers 19.

The element 8 has such shape viewed in plan (in FIGS. 2-4) that its inner peripheral wall or face defines two part-circular portions 26a, 26b which have the same center on the axis 9 of the rotor and subtend the same angle of more than 60 at the center.

The part-circular portions 26a, 26b are extended on each side by segments 27a, b, c, d, which extend in a direction away from the center 9 of the circular path through which the rollers travel.

On one side of the part-circular portions 26a, 26b, the segments 27b, 27c are connected by a curved connecting portion 29 of small radius and, on the side of the portions 26a, 26b opposed to the portion 29, the segments 27a and 27d are connected to an inlet portion 28 and an outlet portion 28 respectively through two portions which are curved in opposite directions. Suitable passages or channels are provided in the element 8 through which the inlet and outlet ends of the pipe 25 extend out of the body.

In the illustrated embodiment, the segments 27a, b, c, d, are rectilinear segments which are tangent to the part-circular portions 260 and 26b and consequently extend in a direction away from the center 9 of these part-circular portions and away from the path of movement of the rollers.

However, it will be understood that the segments 270, b, c, a, could have other shapes, for example that of a parabola or any pipe disengaging curved shape which is such that the pipe extends in a direction which progressively moves away from the circular path of movement of the rollers.

Indeed, so long as these segments extend in a direction away from this path a distance corresponding to the thickness of the pipe 25, they merely serve, in operation of the pump, as means for connection to the portion 29 and to the inlet portion 28 and the outlet portion 28.

It is merely necessary that the segments 27 have such shape that the compression of the pipe 25 along an upstream segment 27 exactly compensates at each instant the volume released by the decompression of the pipe 25 along a downstream segment 27.

The pipe 25 is preferably manufactured to have a configuration identical to that described hereinbefore of the inner face or wall of the element 8 so that it remains in contact with this wall without stress.

In order that the rollers 19 be able to exert a compressing action on the pipe 25, the radius of the partcircular portions 26a, 26b measured between the center 9 and the face of the element 8 is such as to be equal to the distance between the center 9 and the axis of rotation ofa roller 19, plus the radius of a roller, plus the radial thickness of the pipe 25 when the latter is flattened, as clearly shown in FIG. 1. The inner wall of the element 8 constitutes in this way a support ramp or face for the pipe 25.

The operation of the pump will be described with a reference to FIGS. 2-7.

FIGS. 2, 3 and 4 show in plan the rotor 13, an upstream roller 19b, an intermediate roller 19c and a downstream roller 19a, and the pipe 25, the direction of rotation of the rotor 13 being indicated by arrow F.

As seen in FIG. 2, the downstream roller 19a has just travelled through the part-circular portion 26b in completely compressing the pipe 25 against the ramp and urging or expelling the fluid in front of it and is on the point of starting to move away from the pipe 25 and thus allowing the latter to be decompressed owing to the fact that the segment 27d is at this point tangent to the portion 26b and consequently extends in a direction away from the path of movement of the roller.

Simultaneously, the upstream roller 19b has finished the pipe-compressing stage on a part of the segment 27a and travels through the part-circular portion 26a and causes closure of the pipe 25a throughout the extent of the portion 26a.

The progression of the upstream roller 19b along the portion 26a urges or expels the fluid in the downstream direction, this fluid being drawn in through the inlet portion 28 by the pipe 25 which resumes its shape.

Simultaneously, the intermediate roller has just travelled through the part of its path facing the connecting portion 29 in which the pipe 25 is completely relieved of any compression and this roller is on the point of starting to compress the pipe 25 in the segment 270 which, as it is tangent to the portion 26b, extends in a direction toward the path of the rollers from the portion 29.

FIG. 5 shows the pipe 25 closed by the roller 19a in the position of the latter shown in FIG. 2.

It can be seen in FIGS. 3 and 6 that the downstream roller 19a is in the semi-decompression position.

The intermediate roller 190 in the semi-compression position compresses the pipe 25 as the downstream roller 19a decompresses it so that the increase in the internal volume of the pipe resulting from the fact that the downstream roller 19a moves away from the pipe in the tangent segment 27b is exactly compensated at every instant by an equal decrease in this volume resulting from the compression of the pipe by the intermediate roller 19c.

Simultaneously, the upstream roller 19b travels along the part-circular portion 26a throughoutthe extent of which it closes the pipe and discharges the fluid in front of it.

FIG. 4 shows that the downstream roller 19a, in continuing to travel through its circular path, has ceased to FIG. 9, there is illustrated the pipe with inlet and outlets 28 and 28 respectively and having sinusoidal portions 26a and 26b. The rollers 19a, 19b and 19c .move in an elliptical path, each alternately moving compress the pipe 25 and is on the point of moving away from the latter (FIG. 7), the intermediate roller 19c being in its position for completely compressing the pipe 25 and closing the latter through the extent of its travel along the portion 26b and thus urging or expelling the fluid in front of it in a continuous manner until it reaches the junction of this portion with the tangent segment 27d.

At this point, the intermediate roller 19c, in continuing its travel, will be in the position of the downstream roller 19a shown in FIG. 2.

During this time, an exchange similar to the roller closing the pipe in the portion 26a occurs between the downstream roller 19a and upstream roller 19b on the opposed part of the pipe.

The suction or induction of the fluid is ensured merely by the roller 190 during the period during which the rollers 19b and 19a do not close the pipe 25.

Owing to the fact that the rollers 19a, b, c, are driven in rotation by their gear pinions 22 meshed with the teeth of the ring 23, they roll along the pipe with no friction so that there is no wear of the latter and any tendency of the pipe to creep or move in the longitudinal direction is precluded.

It will be understood from the operation just described that the pump according to the invention produces an absolutely regular fluid flow devoid of any pulsations at the inlet and outlet.

Consequently, this pump is particularly adapted for use in perfusion operations on patients.

Although there has been described a preferred embodiment of the pump in which the fixed configuration of the ramp is so arranged that the rollers which describe a circular path are alternately in contact with the pipe and move away from the latter, the same result can be obtained within the scope and spirit of the invention by employing a support ramp of circular shape and a mechanism which imparts to the rollers a radial movement with respect to the plate, for example by means of a cam mechanism or other mechanism such as illustrated in FIG. 8. In this embodiment, the pipe 25 is in a fixed circular configuration, all of the segments 26a, 26b, 27a, 27b, 27c and 27d being circular. The rollers 19a, 19b and 190 move in radial movement by means of a camming mechanism. The direction of rotation is indicated by arrow F. As is obvious from the drawing the rollers alternately move toward and away from support ramp thereby producing an absolutely regular fluid flow devoid of any pulsations at the inlet 28 and outlet 28'.

However, such a mechanism is necessarily more complicated and more expensive to manufacture and for this reason has not been described in more detail.

In another arrangement, the fixed configuration of the pipe can be a sinusoid and the rollers can travel through a closed path having a rectilinear active part or alternatively, the configuration of the pipe can be rectilinear and the rollers can travel through a closed path having a sinusoid active path. These two embodiments are illustrated in FIGS. 9 and 10, respectively. In

away from and towards the pipe along the path. FIG. 10 illustrates a rectilinear section of pipe 25 with the rollers 19a 19b, and moving in a sinusoidal path.

If desired, portions of the pipe corresponding to the inlet portion 28 and outlet portion 28 for the fluid can be transparent and a suitable device 30 for detecting particlescan be disposed on each side of these parts (FIG. 4) .This device can be employed for controlling the pumped fluid and possibly stopping operation of the pump automatically in response to given conditions. However, this arrangement is well known in the art and is not part of the pump and will not be described in detail.

Further, owing to the fact of the regularity of the flow rate the pump according to the invention can also be employed, for example, for maintaining a constant pressure in a reservoir which is filled irregularly, the pump emptying the reservoir and being controlled by the pressure prevailing in the latter.

Having now described our invention what we claim as new and desire to secure by Letters Patent is:

1. A peristaltic pump comprising an elastically yieldable pipe having an inlet part and an outlet part for fluid to be pumped, means defining a support ramp in abutting relation to the pipe and imparting to the pipe a fixed configuration, at least three movable pressing elements, and drive means for causing the elements to travel around an axis in a closed path which encounters said configuration so as to compress the pipe and move away from the pipe alternately, the fixed configuration imparted to the pipe by the ramp, the path of said elements and spacing between said elements being such that when the element which is the downstream element relative to the direction in which the fluid is pumped through the pipe moves away from the pipe an upstream element already closes the pipe and causes the fluid to progress as the downstream element causes a decompression of the pipe, the intermediate element located between the upstream element and downstream element progressively compressing the pipe so as to ensure an exact volumetric compensation, at each instant, of the decompression due to the downstream element by the compression due to the intermediate element.

2. A peristaltic pump comprising an elastically yieldable pipe having an inlet end and an outlet end for fluid to be pumped, means defining a support ramp combined with the pipe and imparting to the pipe a fixed configuration, means defining a rotor rotatable about an axis and located within said support ramp, at least three rolling elements rotatably mounted on the rotor in angularly evenly spaced relation to each other, rotation of the rotor causing said elements to rotate about said axis in a closed 'path, the support ramp having a configuration comprising two part-circular portions which have the same center on said axis and the same radius and subtend an angle of substantially 60 on said axis, a curved connecting portion tangent to the part-circular portions and interconnecting the part-circular portions and in which connecting portion the pipe does not meet the path of said elements, an inlet portion and an outlet portion respectively adjacent said inlet part and outlet part of the pipe and tangent to the part-circular portions, the radius of the part-circular portions being equal to the sum of the distance between said axis and the center of a rolling element plus the radius of the rolling element plus the thickness of the pipe when the pipe is completely flattened against the ramp by the rolling element.

3. A pump as claimed in claim 1, wherein said drive means are adapted to cause said elements to move alternately toward and away from the ramp which has a fixed substantially circular configuration.

4. A pump as claimed in claim 1, wherein said fixed configuration of the pipe is a sinusoid, said path having a rectilinear active part.

5. A pump as claimed in claim 1, wherein said configuration is rectilinear.

6. A pump as claimed in claim 2, further comprising a fixed ring gear having internal gear teeth and a gear pinion integral with each rolling element and in meshed relation to said ring gear.

7. A pump as claimed in claim 6, wherein said rolling elements are mounted on the rotor at equal distances from said axis.

8. A pump as claimed in claim 6, comprising a shaft for driving the rotor and a unidirectional coupling device drivingly connecting the shaft to the rotor.

9. A pump as claimed in claim 1, wherein said inlet part and outlet part of the pipe are transparent and a device for detecting particles is disposed on each side of said transparent parts.

10. A pump as claimed in claim 1, wherein said pressing elements are rotatable rollers. 

1. A peristaltic pump comprising an elastically yieldable pipe having an inlet part and an outlet part for fluid to be pumped, means defining a support ramp in abutting relation to the pipe and imparting to the pipe a fixed configuration, at least three movable pressing elements, and drive means for causing the elements to travel around an axis in a closed path which encounters said configuration so as to compress the pipe and move away from the pipe alternately, the fixed configuration imparted tO the pipe by the ramp, the path of said elements and spacing between said elements being such that when the element which is the downstream element relative to the direction in which the fluid is pumped through the pipe moves away from the pipe an upstream element already closes the pipe and causes the fluid to progress as the downstream element causes a decompression of the pipe, the intermediate element located between the upstream element and downstream element progressively compressing the pipe so as to ensure an exact volumetric compensation, at each instant, of the decompression due to the downstream element by the compression due to the intermediate element.
 2. A peristaltic pump comprising an elastically yieldable pipe having an inlet end and an outlet end for fluid to be pumped, means defining a support ramp combined with the pipe and imparting to the pipe a fixed configuration, means defining a rotor rotatable about an axis and located within said support ramp, at least three rolling elements rotatably mounted on the rotor in angularly evenly spaced relation to each other, rotation of the rotor causing said elements to rotate about said axis in a closed path, the support ramp having a configuration comprising two part-circular portions which have the same center on said axis and the same radius and subtend an angle of substantially 60* on said axis, a curved connecting portion tangent to the part-circular portions and interconnecting the part-circular portions and in which connecting portion the pipe does not meet the path of said elements, an inlet portion and an outlet portion respectively adjacent said inlet part and outlet part of the pipe and tangent to the part-circular portions, the radius of the part-circular portions being equal to the sum of the distance between said axis and the center of a rolling element plus the radius of the rolling element plus the thickness of the pipe when the pipe is completely flattened against the ramp by the rolling element.
 3. A pump as claimed in claim 1, wherein said drive means are adapted to cause said elements to move alternately toward and away from the ramp which has a fixed substantially circular configuration.
 4. A pump as claimed in claim 1, wherein said fixed configuration of the pipe is a sinusoid, said path having a rectilinear active part.
 5. A pump as claimed in claim 1, wherein said configuration is rectilinear.
 6. A pump as claimed in claim 2, further comprising a fixed ring gear having internal gear teeth and a gear pinion integral with each rolling element and in meshed relation to said ring gear.
 7. A pump as claimed in claim 6, wherein said rolling elements are mounted on the rotor at equal distances from said axis.
 8. A pump as claimed in claim 6, comprising a shaft for driving the rotor and a unidirectional coupling device drivingly connecting the shaft to the rotor.
 9. A pump as claimed in claim 1, wherein said inlet part and outlet part of the pipe are transparent and a device for detecting particles is disposed on each side of said transparent parts.
 10. A pump as claimed in claim 1, wherein said pressing elements are rotatable rollers. 